/* ===== Reset & Base ===== */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg: #ffffff;
    --bg-alt: #f8f9fb;
    --surface: #ffffff;
    --surface-hover: #f3f4f6;
    --border: #d9dde5;
    --border-light: #eceff3;
    --text: #111827;
    --text-muted: #4b5563;
    --text-light: #6b7280;
    --accent: #245b83;
    --accent-light: #174766;
    --accent-bg: #eef4f8;
    --accent-border: #c8d7e3;
    --confirmed-bg: #eef7f1;
    --confirmed-color: #166534;
    --confirmed-border: #c8e6d0;
    --tentative-bg: #fff7ed;
    --tentative-color: #9a5b00;
    --tentative-border: #f2d2a0;
    --radius: 6px;
    --radius-lg: 8px;
    --shadow-sm: none;
    --shadow: none;
    --shadow-lg: none;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: var(--accent-light);
}

a:focus-visible,
.nav-link:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 3px;
    border-radius: 3px;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Hero ===== */
.hero {
    position: relative;
    padding: 68px 0 52px;
    text-align: center;
    overflow: hidden;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-venue {
    display: block;
    font-size: 0.82rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 16px;
}

.hero-title {
    font-size: clamp(2.1rem, 4.4vw, 3.25rem);
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: 0;
    margin-bottom: 16px;
    color: var(--text);
}

.hero-subtitle {
    font-size: clamp(1.35rem, 3vw, 2.1rem);
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 32px;
}

.hero-meta {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 6px 22px;
}

.meta-pill {
    font-size: 0.86rem;
    color: var(--text-muted);
}

/* ===== Nav ===== */
.nav-bar {
    position: sticky;
    top: 0;
    background: #ffffff;
    border-bottom: 1px solid var(--border);
    z-index: 100;
    transition: box-shadow 0.3s;
}

.nav-bar.stuck {
    box-shadow: 0 1px 12px rgba(0, 0, 0, 0.06);
}

.nav-inner {
    display: flex;
    justify-content: center;
    gap: 6px;
    padding: 10px 0;
    overflow-x: auto;
}

.nav-link {
    font-size: 0.88rem;
    font-weight: 500;
    padding: 6px 16px;
    border-radius: 4px;
    color: var(--text-muted);
    transition: background 0.2s, color 0.2s;
    white-space: nowrap;
}

.nav-link:hover {
    background: var(--bg-alt);
    color: var(--text);
}

/* ===== Sections ===== */
.section {
    padding: 60px 0;
    scroll-margin-top: 72px;
}

.section-alt {
    background: var(--bg-alt);
}

.section-title {
    font-size: 1.85rem;
    font-weight: 700;
    margin-bottom: 12px;
    letter-spacing: -0.01em;
    color: var(--text);
    text-align: center;
}

.section-title::after {
    content: '';
    display: block;
    width: 40px;
    height: 2px;
    margin: 12px auto 0;
    border-radius: 2px;
    background: var(--accent);
}

.section-desc {
    color: var(--text-muted);
    margin-bottom: 28px;
    max-width: 760px;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

.section-desc.centered {
    max-width: 720px;
    margin-left: auto;
    margin-right: auto;
}

/* ===== About ===== */
.about-content {
    text-align: center;
}

.about-content p {
    max-width: 760px;
    margin: 0 auto 14px;
    color: var(--text-muted);
    font-size: 1.02rem;
}

.about-content em {
    color: var(--accent);
    font-style: italic;
}

.about-content strong {
    color: var(--text);
    font-weight: 600;
}

.scaling-figure {
    max-width: 860px;
    margin: 22px auto 36px;
}

.scaling-figure img {
    display: block;
    width: 100%;
    height: auto;
    border: 1px solid var(--border);
    border-radius: var(--radius);
}

/* ===== Speakers ===== */
.question-grid,
.interaction-grid {
    display: grid;
    gap: 18px;
    margin-top: 28px;
}

.question-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.interaction-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.question-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 22px;
    text-align: left;
    box-shadow: 0 8px 24px rgba(17, 24, 39, 0.04);
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.question-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent-border);
    box-shadow: 0 10px 28px rgba(17, 24, 39, 0.06);
}

.question-card h3 {
    color: var(--text);
    font-size: 1.05rem;
    font-weight: 600;
    line-height: 1.35;
    margin-bottom: 10px;
}

.question-card h3::before {
    content: '';
    display: block;
    width: 28px;
    height: 3px;
    margin-bottom: 12px;
    border-radius: 3px;
    background: var(--accent);
}

.question-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.interaction-card {
    min-height: 360px;
    border-radius: var(--radius-lg);
    perspective: 1200px;
    outline: none;
}

.interaction-inner {
    position: relative;
    min-height: 360px;
    transform-style: preserve-3d;
    transition: transform 0.65s cubic-bezier(0.2, 0.7, 0.2, 1);
}

.interaction-card:hover .interaction-inner,
.interaction-card:focus .interaction-inner,
.interaction-card:focus-within .interaction-inner {
    transform: rotateY(180deg);
}

.interaction-face {
    position: absolute;
    inset: 0;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    backface-visibility: hidden;
    box-shadow: 0 8px 24px rgba(17, 24, 39, 0.04);
}

.interaction-front {
    justify-content: space-between;
    text-align: center;
}

.interaction-front img {
    width: 100%;
    min-height: 270px;
    flex: 1;
    padding: 18px;
    background: #ffffff;
    object-fit: contain;
}

.interaction-front h3 {
    padding: 16px 18px 18px;
    border-top: 1px solid var(--border-light);
}

.interaction-back {
    justify-content: flex-start;
    padding: 24px;
    text-align: left;
    transform: rotateY(180deg);
}

.interaction-card h3 {
    color: var(--text);
    font-size: 1.05rem;
    font-weight: 600;
    line-height: 1.35;
}

.interaction-back h3 {
    margin-bottom: 12px;
}

.interaction-card p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.interaction-card:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 4px;
}

.speakers-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 18px;
    margin-top: 28px;
}

.speaker-card {
    flex: 0 0 220px;
    width: 220px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px 18px;
    text-align: center;
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.speaker-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent-border);
    box-shadow: 0 4px 14px rgba(17, 24, 39, 0.05);
}

.speaker-photo {
    width: 80px;
    height: 80px;
    margin: 0 auto 14px;
    border-radius: 50%;
    object-fit: cover;
    object-position: center 20%;
    border: 2px solid var(--border-light);
}

.speaker-card h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 3px;
    color: var(--text);
}

.speaker-affil {
    font-size: 0.83rem;
    color: var(--text-light);
    margin-bottom: 12px;
}

.status-badge {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 3px 10px;
    border-radius: 4px;
}

.status-badge.confirmed {
    background: var(--confirmed-bg);
    color: var(--confirmed-color);
    border: 1px solid var(--confirmed-border);
}

.status-badge.tentative {
    background: var(--tentative-bg);
    color: var(--tentative-color);
    border: 1px solid var(--tentative-border);
}

/* ===== Schedule ===== */
.schedule-table {
    margin-top: 20px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.schedule-row {
    display: grid;
    grid-template-columns: 160px 1fr 320px;
    gap: 16px;
    padding: 13px 24px;
    border-bottom: 1px solid var(--border-light);
    align-items: center;
    font-size: 0.92rem;
}

.schedule-row:last-child {
    border-bottom: none;
}

.schedule-row:hover {
    background: var(--bg-alt);
}

.schedule-header {
    background: var(--bg-alt);
    font-weight: 600;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-light);
}

.schedule-row.break {
    background: #fafafa;
    color: var(--text-light);
    font-style: italic;
}

.schedule-row.talk .sched-event {
    color: var(--accent);
    font-weight: 500;
}

.sched-time {
    font-variant-numeric: tabular-nums;
    color: var(--text-muted);
    font-weight: 500;
}

.sched-format {
    font-size: 0.85rem;
    color: var(--text-light);
}

/* ===== CFP ===== */
.cfp-content {
    margin-top: 20px;
    max-width: 760px;
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

.cfp-content.left-content {
    text-align: left;
}

.cfp-content>p {
    font-size: 1.02rem;
    color: var(--text-muted);
    margin-bottom: 28px;
    max-width: 720px;
    margin-left: auto;
    margin-right: auto;
}

.left-content>p {
    margin-left: 0;
    margin-right: 0;
}

.left-content .cfp-topics h3,
.left-content .cfp-dates h3 {
    text-align: left;
}

.cfp-topics,
.cfp-dates {
    margin-bottom: 28px;
}

.cfp-topics h3,
.cfp-dates h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 14px;
    color: var(--text);
}

.cfp-topics p {
    max-width: 720px;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.left-content .cfp-topics ul {
    display: block;
}

.cfp-topics ul {
    display: inline-block;
    max-width: 100%;
    list-style: disc;
    padding-left: 22px;
    text-align: left;
}

.cfp-topics li {
    padding: 6px 0;
    color: var(--text-muted);
    font-size: 0.93rem;
}

.date-row {
    display: flex;
    justify-content: space-between;
    max-width: 520px;
    margin-left: auto;
    margin-right: auto;
    padding: 9px 0;
    border-bottom: 1px solid var(--border-light);
    font-size: 0.93rem;
    gap: 20px;
    text-align: left;
}

.left-content .date-row {
    max-width: none;
    margin-left: 0;
    margin-right: 0;
}

.date-label {
    color: var(--text-muted);
}

.date-value {
    font-weight: 600;
    color: var(--text);
}

/* ===== Organizers ===== */
.organizers-grid {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 18px;
    margin-top: 28px;
}

.organizer-card {
    flex: 0 0 190px;
    width: 190px;
    text-align: center;
    padding: 24px 14px 20px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.organizer-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent-border);
    box-shadow: 0 4px 14px rgba(17, 24, 39, 0.05);
}

.org-photo {
    width: 72px;
    height: 72px;
    margin: 0 auto 12px;
    border-radius: 50%;
    object-fit: cover;
    object-position: center 20%;
    border: 2px solid var(--border-light);
}

.organizer-card h3 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 3px;
}

.organizer-card h3 a {
    color: var(--text);
}

.organizer-card h3 a:hover {
    color: var(--accent);
}

.organizer-card p {
    font-size: 0.8rem;
    color: var(--text-light);
}

/* ===== Sponsors ===== */
.sponsors-grid {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 40px;
    flex-wrap: wrap;
    margin-top: 28px;
}

.sponsor-link {
    display: inline-block;
}

.sponsor-link:hover {
    opacity: 0.8;
}

.sponsor-logo {
    max-height: 80px;
    max-width: 280px;
    object-fit: contain;
}

/* ===== Footer ===== */
.footer {
    padding: 36px 0;
    text-align: center;
    border-top: 1px solid var(--border);
    color: var(--text-light);
    font-size: 0.86rem;
    background: var(--bg-alt);
}

.footer-contact {
    margin-top: 6px;
}

.footer-contact a {
    color: var(--accent);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .hero {
        padding: 70px 0 50px;
    }

    .hero-meta {
        row-gap: 6px;
    }

    .section {
        padding: 48px 0;
    }

    .schedule-row {
        grid-template-columns: 1fr;
        gap: 4px;
        padding: 12px 16px;
    }

    .schedule-header {
        display: none;
    }

    .sched-format {
        font-size: 0.8rem;
    }

    .date-row {
        flex-direction: column;
        align-items: center;
        gap: 2px;
        text-align: center;
    }

    .speaker-card {
        flex-basis: 160px;
    }

    .organizer-card {
        flex-basis: 140px;
    }

    .question-grid,
    .interaction-grid {
        grid-template-columns: 1fr;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
}